The present invention relates to di-N-substituted piperazines and 1,4-di-substituted piperidines useful in the treatment of cognitive disorders, pharmaceutical compositions containing the compounds, methods of treatment using the compounds, and to the use of said compounds in combination with acetylcholinesterase inhibitors.
Alzheimer's disease and other cognitive disorders have received much attention lately, yet treatments for these diseases have not been very successful. According to Melchiorre et al. (J. Med. Chem. (1993), 36, 3734-3737), compounds that selectively antagonize M2 muscarinic receptors, especially in relation to M1 muscarinic receptors, should possess activity against cognitive disorders. Baumgold et al. (Eur. J. of Pharmacol., 251, (1994) 315-317) disclose 3-.alpha.-chloroimperialine as a highly selective m2 muscarinic antagonist.
The present invention is predicated on the discovery of a class of di-N-substituted piperazines and 1,4-di-substituted piperidines, some of which have m2 selectivity even higher than that of 3-.alpha.-chloroimperialine. Logemann et al (Brit. J. Pharmacol. (1961), 17, 286-296) describe certain di-N-substituted piperazines, but these are different from the inventive compounds of the present invention. Furthermore, the compounds of Logemann et al. are not disclosed to have activity against cognitive disorders.